Polycarbonate resins are broadly used in various fields due to good mechanical and thermal properties thereof. Particularly, polycarbonate resins have good properties in terms of transparency, hygienic properties, rigidity, and heat resistance, and are broadly used as materials for medical supplies for medical devices, surgical instruments, and the like. Such medical products are required to be completely sterilized, and examples of such sterilization methods include contact treatment with sterilized gas such as ethylene oxide, heat treatment in an autoclave, ionizing radiation treatment with gamma radiation, electron beams and X-rays, and the like. Among these methods, contact treatment with ethylene oxide is undesirable due to toxicity and instability of ethylene oxide, and environmental problems caused by waste disposal. In addition, heat treatment in the autoclave can cause deterioration of the polycarbonate resin during treatment at high temperature and requires high energy costs and a drying process due to moisture remaining on a treated part. Therefore, sterilization treatment by irradiation with ionizing radiation, which can be performed at low temperature and is relatively economical, is typically used in the art.
However, it is proposed to stabilize the polycarbonate resin by adding various additives thereto since the polycarbonate resin causes yellowing and property deterioration when irradiated with ionizing radiation. For example, it is known in the art that a polycarbonate resin composition containing a poly(oxyalkylene) derivative and/or a sulfur-containing compound can be stabilized against ionizing radiation for sterilization. Specifically, the polycarbonate resin composition containing a poly(oxyalkylene) derivative and/or a sulfur-containing compound includes a resin composition containing a poly(oxyalkylene) derivative and a disulfide, a resin composition containing a poly(oxyalkylene) derivative and sulfoxide or sulfone, a resin composition containing a poly(oxyalkylene) derivative and a sulfonate, and a resin composition containing a poly(oxyalkylene) derivative and a sulfonamide, and the like.
However, such a polycarbonate resin composition is not sufficiently stabilized against yellowing. Moreover, the polycarbonate resin composition containing a sulfur-containing compound can cause molecular weight reduction, having an adverse effect on the physical properties of the polycarbonate resin.
Therefore, there is a need for development of a polycarbonate resin composition which has good properties in terms of discoloration resistance, color (brightness), hydrolysis resistance and flame retardancy after irradiation with ionizing radiation so as to be applicable to ionizing radiation-resistant medical supplies.
The background technique of the present invention is disclosed in U.S. Pat. No. 6,166,116.